Due to the increasing demand for more data storage, heat assisted or energy assisted magnetic recording concepts have been pursued as ways to achieve higher density magnetic recording. In an energy-assisted magnetic recording (EAMR) system, local heating is utilized to heat up a recording medium such that the coercivity of the recording medium can be reduced. With the coercivity of the heated location of the recording medium being temporarily reduced, an applied magnetic writing field can more easily direct the magnetization of the recording medium. The recording density is mainly controlled by the minimum thermal spot size in the recording medium that is produced by an optical near field transducer (NFT) at the excitation state (e.g., surface plasmon-resonance). Therefore, the reliability of the EAMR system is generally affected by the thermal stability of the recording media.